In　this　work,　we　synthesized　six　polycyclic　heterocyclic　quinones　(PHQs)　and　one　unexpected　product　(compound　6).　We　verified　all　of　their　structures　by　1HNMR,　13CNMR,　and　HRMS　and　obtained　four　crystal　structures　of　the　seven　products.　At　first,　we　compared　the　crystal　structures　with　crystal　structures　similar　to　those　reported　in　the　literature　and　explained　their　differences　by　conjugative　effect,　hyperconjugative　effect,　and　electrostatic　effect.　Then,　we　compared　the　crystal　structure　of　compound　6　with　the　calculated　structure　of　compound　6.　The　natural　bond　orbital　analysis　showed　that　the　calculated　structure　formed　intramolecular　hydrogen　bonds,　whereas　the　crystal　structure　formed　intermolecular　hydrogen　bonds　but　not　intramolecular　hydrogen　bonds.　The　main　reason　for　this　difference　was　not　due　to　the　atomic　charge　or　the　interatomic　distance,　but　rather　the　energy　levels　of　the　orbitals　of　the　lone-pair　electrons.　In　crystal　structures,　the　intermolecular　interactions　contained　many　weak　interactions,　and　we　used　the　hydrogen　atom　substitution　(HAS)　method　to　divide　the　total　intermolecular　interactions　as　several　independent　weak　interactions　and　to　calculate　their　energies.　The　HAS　method　was　often　successful　if　the　substituted　group　did　not　have　a　strong　effect　on　the　electronic　structure　of　the　entire　molecule,　and　we　found　examples　in　the　calculations　of　energies　of　weak　interactions　of　crystal　structure　of　compound　6　and　compound　3a.　An　unsuccessful　example　of　the　HAS　method　was　the　substitution　of　C　=　O　group　with　CH2　group　to　eliminate　the　O…H-N　hydrogen　bond　interaction　from　the　total　interaction.　According　to　the　HAS　method,　our　calculations　showed　that　the　strength　order　of　the　weak　interactions　was　as　follows:　π-π　stacking　＞　hydrogen　bond　＞　n-π　stacking　＞　σ-π　stacking.　For　the　hydrogen　bond,　the　strength　order　was　as　follows:　C　=　O…H-N　＞　C–Cl…H-N　＞　C-F…H-N.　For　n-π　stacking　interaction,　the　strength　order　was　as　follows:　Cl-π　＞　N-π　＞　F-π.　Finally,　we　selected　five　synthesized　PHQs　to　test　anticancer　activities　and　some　of　them　showed　better　anticancer　activities　than　the　positive　control　drugs.　©　2024